yeah that was kind of a suprise for me too but i abandoned a quest when i saw this freakishly powerful rathalos and when you have to get 10 coal pieces for the village quest and there is a Iodrome and Kut-ku in it
When i did that quest i saw nothing, if there was those two i would just stop
Lol. Usually Rathalos once you've done it. Here's another one:
You just placed a pitful trap, and the wyvern flys away to another area.
Or, you just started a quest and you weren't paying attention and died straight away
Thats happened to me once.